College of Engineering, Huazhong Agricultural University, Wuhan, 430070, China.
College of Engineering, Huazhong Agricultural University, Wuhan, 430070, China; Key Laboratory of Smart Farming for Agricultural Animals, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, China.
J Environ Manage. 2024 Jun;362:121349. doi: 10.1016/j.jenvman.2024.121349. Epub 2024 Jun 4.
The use of Ni-based catalysts is a common method for eliminating tar through catalytic cracking. Carbon deposition is the main cause of deactivation in Ni/ZSM-5 catalysts, with filamentous MWCNTs being the primary form of carbon deposits. This study investigates the formation and evolution of CNTs during the catalytic process of biomass tar to explore the mechanism behind carbon deposition. The effect of the 9Ni/10MWCNTs/81ZSM-5 on toluene reforming was investigated through a vertical furnace. Gases produced by tar catalysis were evaluated through GC analysis. The physicochemical structure, properties and catalytic performance of the catalyst were also tested. TG analysis was used to assess the accumulation and oxidation reactivity of carbon on the catalyst surface. An analysis was conducted on the mechanism of carbon deposition during catalyst deactivation in tar catalysis. The results showed that the 9Ni/91ZSM-5 had a superior toluene conversion of 60.49%, but also experienced rapid and substantial carbon deposition up to 52.69%. Carbon is mainly deposited as curved filaments on both the surface and pore channels of the catalyst. In some cases, tip growth occurs where both carbon deposition and Ni coexist. Furthermore, specific surface area and micropore volume are reduced to varying degrees due to carbon deposition. With the time increased, the amount of carbon deposited on the catalyst surface increased to 62.81%, which gradually approached saturation, and the overall performance of the catalyst was stabilized. This situation causes toluene molecules to detach from the active sites within the catalyst, hindering gas release, which leads to reduced catalytic activity and further carbon deposition. It provides both a basis for the development of new catalysts and an economically feasible solution for practical tar reduction and removal.
镍基催化剂的使用是通过催化裂化消除焦油的常用方法。积碳是 Ni/ZSM-5 催化剂失活的主要原因，丝状 MWCNTs 是主要的积碳形式。本研究通过生物质焦油催化过程考察 CNTs 的形成和演变，以探索积碳的机理。通过垂直炉考察了 9Ni/10MWCNTs/81ZSM-5 对甲苯重整的影响。通过 GC 分析评估焦油催化产生的气体。还测试了催化剂的物理化学结构、性能和催化性能。通过 TG 分析评估催化剂表面碳的积累和氧化反应性。分析了焦油催化过程中催化剂失活时碳沉积的机理。结果表明，9Ni/91ZSM-5 的甲苯转化率为 60.49%，但也经历了快速且大量的碳沉积，达到 52.69%。碳主要以弯曲的丝状沉积在催化剂的表面和孔道上。在某些情况下，碳沉积和 Ni 共存会发生尖端生长。此外，由于碳沉积，比表面积和微孔体积都有不同程度的降低。随着时间的增加，催化剂表面沉积的碳量增加到 62.81%，逐渐趋于饱和，催化剂的整体性能得到稳定。这种情况导致甲苯分子从催化剂的活性位上脱离，阻碍了气体的释放，从而降低了催化活性和进一步的碳沉积。它为新型催化剂的开发提供了基础，并为实际焦油的减少和去除提供了经济可行的解决方案。
